Satellite Navigation Buying Guide
The days of the old fashion map seem to becoming numbered due to the increase in popularity of satellite navigation systems or Global Positioning Systems (GPS). As this technology has become more popular it has advanced and taken on various different forms and functionalities. You can now use these devices for road, marine and even mapping walking routes. So depending on the function you want to use your GPS system to fulfil, will determine the model that is suitable for you.
Types
It is now possible to buy handheld, portable GPS units, these are small and as such very transportable and versatile. You can use them for anything from planning a walking route or finding a specific location along with most other navigation activities that were once the soul responsibility of the map but with the added bonus of being able to give you your exact current location in relation to certain waypoints (recognised location reference points). As an extension to this you can also opt for fitness options, they will monitor speed rates and distances, whilst also allowing you to plot your favourite running routes. As the entry level to the market you can expect to pay from £50-£150 for one of these models.
As the next step up from the basic device you can go for point of interest models that can store areas of interest for example a recognised building such as a shopping centre. They will also often allow you to connect to a PC and download additional points of interest to the GPS internal memory. Due to the extended features these units provide they are of course more expensive, probably ranging from £150-£250.
In-car systems are the most popular GPS technology around right now, these are normally mounted units that attached to the window or dashboard of the car to provide easy viewing of possible routes for drivers. They are slightly larger than portable systems and so can support extra features such as built in maps. Most will give you a journey planner based on your current position and your destination, they will then guide you step by step (often voice guided) to your desired location. Other models will also offer addition features such as up to date traffic reports. GPS software system are also available that will enable you to turn your computer, or the more popular option, your PDA into a fully functional GPS unit but this will require the original device to be compatible with the software so do check before you make a purchase.
Chart plotter GPS systems are used for water navigation. They have similar features you may find on a road navigation system only for water systems but they will also come with some additional features. Features may include tide time tables or depth finders and water temperature gauges and also they will often include fish finders, these are devices that detect areas of mass under water helping fishermen find schools of fish. For marine or driving GPS units you should expect to pay £200 at the bottom end of the market and up to £600 for the most advanced models.
Display Size:
Display
At a basic level most GPS systems will support a Gray display and a backlight, however in dark condition this may be a little hard to view easily. In this case you may want to consider a coloured display system but with this option your battery life will reduce. The size of the display will also be affect by the screen size, on average a GPS screen will be around 2-4 inches but for portable devices this may be smaller and for models with an increased number of features such as a chart plotter device this screen size will probably increase.
Display Size:
Display:
Waterproof
If you are using your GPS unit outside then you will probably want it to be fairly weather resistant. You will find it hard to find any that are 100% waterproof but they will offer varying levels of water resistance, look out for an IPX7 rating, this means they can withstand up to 3 feet of water for half an hour. An IPX4 rating means the device should stand up to rain but an IPX2 rating means it is not advisable that you expose the device to any water as it will probably not hold up to it.
Waterproof:
Memory
Memory is an important factor to consider when choosing a GPS unit, as this will determin how many routes you can save. If you do a lot of travelling you will probably want a device that can store a large number of possible journeys. On average a middle of the range GPS unit will have around 32mb of memory but this can be a lot more or less depending on the sophistication of the model. You will have some units that provide software that allows you to store information onto your computer, reducing the amount of internal memory you need to use. Aside from this you can also buy extended memory for some models much the same way you buy memory cards for digital cameras, laptops or other computing devices.
Memory:
Connectivity
If you do plan in using your GPS system in conjunction with another device such as a PC or PDA you will need to take note of the connectivity options the unit supports. The most common interface method is USB connectors, most computers will support these and GPS units with USB adaptors will be able to transfer information to another device. On high-grade models you might have Bluetooth connectivity. Bluetooth is a wireless connection that allows electronic devices to connect and transfer data between one another. This requires no cables and will work up to around 10 metres between the two devices. A slight alteration on this technology is infrared, this operates in much the same way as Bluetooth but it requires the two devices to be in line of sight of each other to work effectively. Do check the connectivity though as some basic models will come with no interface capabilities at all.
Connectivity:
Navigation System
GPS systems work by receiving signals from satellites in order to pin point your exact location. However GPS signals are fairly weak and so at least three or four signals need to be lock in on to gain an accurate location. Most handheld units are 12 channel receivers meaning they can track up to twelve satellites at any one time but more advanced models will have a larger capacity. Normally this will allow you to accurately find your position within a 40-metre radius but often more accurately. Depending on the system you are using this will be closer, with a Wide Area Augmentation System (WAAS) this distance can be reduced to around 4-metres and other similar systems but there are less widely used systems such as Sirf , ENGOS, MAMS or NAVTEG, accuracy will differ between around 3 metres up to roughly 40 metres. Obviously if you are using your GPS system to find very specific locations, such as a building, you want it to be as accurate as possible so do check the area of accuracy the system works to.